The tech giant has insisted the project is for "non-offensive uses only"
Google has confirmed that its artificial intelligence software is being used by the Pentagon as part of efforts to analyse drone footage.
It marks a rare example of the tech giant partnering with the US military on a 'pilot project', although the company has insisted that the project is not related to combat.
Gizmodo first reported the news, saying the development had set off a "firestorm among employees".
According to the report, some staff were "outraged" the company would offer resources for use in drone operations.
It is reported to come as part of the Pentagon's Project Maven - or Algorithmic Warfare Cross-Functional Team (AWCFT).
The project was launched last year, with US officials saying it was to "accelerate [Department of Defence's] integration of big data and machine learning".
Initial phases of the project are focused on computer vision algorithms for object detection and classification, before plans to move on to more advanced vision technology.
In a statement quoted by Gizmodo, a Google spokesperson said: "This specific project is a pilot with the [US] Department of Defence, to provide open source TensorFlow APIs that can assist in object recognition on unclassified data. The technology flags images for human review, and is for non-offensive uses only.
"Military use of machine learning naturally raises valid concerns. We’re actively discussing this important topic internally and with others as we continue to develop policies and safeguards around the development and use of our machine learning technologies."
Eric Schmidt - the then executive chairman of Google's parent company Alphabet - last year spoke about worries within tech firms of the potential uses of artificial intelligence for military purposes.
He observed: "There’s a general concern in the tech community of somehow the military-industrial complex using their stuff to kill people incorrectly, if you will.
"My guess is what will happen is that there will be tech companies founded that are more in alignment with the mission and values of the military, that will use this technology to help keep the country safe."
Mr Schmidt is a head of the Defence Innovation Advisory Board in the US, which brings together prominent figures from Silicon Valley to "enhance the Defence Department's culture, organisation and processes".
Drone strikes have become an increasingly common element of US military operations, for both surveillance and strike operations.
The Bureau of Investigative Journalism reports that upwards of 10,000 people have been killed in US drone strikes in Pakistan, Afghanistan, Yemen and Somalia.